Reproducibility of ecological data

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After twenty years of procrastination one of our bluest datasets has finally been analysed! The data was one of two sets of data used in a ‘many analysts’ study to look at how the choices that are made in an analysis pathway affects outcomes. The study is covered in a news story published today in Nature.

https://www.nature.com/articles/d41586-023-03177-1

The dataset was one of two that were analysed by 246 biologists in the study which is available online. The variation in the outcomes was remarkable given that all analysts started with the same dataset and were addressing the same question – how is nestling growth affected by the number of siblings that offspring have in the nest. There is continuous variation in the effect that analysts found. A number of analyses found significant positive effects, many found no effect and the majority found significant negative effects of siblings on growth. The study is revealing about the robustness of results in ecology and should hopefully help lead to a different approach to analyses in the future.

Congratulations to Frigg

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Frigg Speelman recently won the Macquarie University 3MT competition. The challenge of this competition is to deliver a three minute verbal presentation summarising the focus of her thesis. Frigg’s success was covered by a nice article in the Macquarie Newsletter here.

Frigg missed the award ceremony as she was in the field, catching chirupping wedgebills

THE UNEXPLORED BENEFITS OF JUST HANGING OUT IN A SOCIAL HOTSPOT

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Our attempts to understand avian behaviour usually focus on important components of life such as foraging, territorial defence, breeding and anti-predation strategies. In our study of the zebra finch, led by Hugo Loning, and a collaboration between researchers from Wageningen University (Netherlands), and Macquarie University (Australia), we focused our attention on what the birds are doing in their downtime – the bits of the day when they aren’t actively engaged in other behaviours, and are just ‘hanging out’.​ The habitat of the study site near Fowlers Gap research station is a very open grassland with small patches of acacia trees, such as those in this ephemeral creek line.

The study was conducted at Fowlers Gap Arid Zone Research Station in arid Australia where a wild population of zebra finches has been the focus of research for 19 years. We identified a number of specific trees or bushes throughout the study area that were frequented on a regular basis by groups of zebra finches. These locations, identified as ‘social hotspots’ were not obviously different from other bushes or trees in the same area, either structurally, or in their position. However, they were the focus of prolonged social gatherings over the course of the study, and anecdotally some had been in use consistently for several years. The social hotspots were identified both by the frequent presence of zebra finches in them, but also by a significant accumulation of zebra finch droppings underneath them. One of the social hotspots was found in the dead tree to the left of this picture. Social hotspots were found in both living and dead trees, and they didn’t differ in an obvious way from other trees or bushes in the local vicinity. Large accumulations of droppings were found underneath social hotspots, indicating their prolonged use by large numbers of birds.

In our study, we characterised social hotspots using direct observational work and longer-term acoustic monitoring. The social dynamics of the hangouts were quite complex, with birds typically arriving and departing in smaller groups, rather than all in a single group. Social gatherings could collectively last for hours at a time, even though individuals came and went, and probably few were present for the whole duration of the hangout.

There were birds present in these social hotspots for over 35% of the hours of daylight, and consequently, these specific locations provided individuals with a good opportunity to find and meet conspecifics from the local population. Although zebra finches usually moved around the local area in pairs, or small groups, the social hangouts were occupied by an average of about 30 birds, with as many as 77 birds hanging out together in a typical acacia tree about 3m wide and 3m tall. The social hotspots therefore provided lots of opportunity for social interactions with many birds from the local population, and there was typically a consistent level of vocalisations, including lots of singing, by multiple males.

Although our study was unable to follow individual movements or participation in these social gatherings, we suggest that social hotspots and hangouts such as those that we have described in the zebra finch are an important, and often neglected part of social behaviour in birds. They will provide a relatively safe refuge during the day where individuals can take advantage of safety in numbers, whilst resting, preening, and socialising with conspecifics.

Further study of such social hotspots should provide insight into their capacity to increase social networking opportunities and information exchange across the wider population. We believe that social hotspots and hangouts are a neglected feature of the behavioural ecology of many social birds and are worthy of further attention.

Tracking sperm and testosterone over reproductive stages in the zebra finch

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Sometimes it takes a while to get studies out….. Finally this week our paper describing the variation in sperm and testosterone over the breeding cycle was published in Hormones and Behaviour. The study was initiated back in 2011 through discussions between Kate Buchanan, Melissah Rowe and myself. The study was supported by funds from the Australian Research Council awarded in 2012 and then conducted by Lori Hurley as part of her PhD. Two postdocs, Ondi Crino and Riccardo Ton have also made significant contributions to the study, by dealing with a complicated dataset and writing the manuscript.

The study characterises variation in the level of testosterone circulating in the blood of males across different stages of the breeding cycle (nesting, egg-laying period, incubation, and nestling rearing), and how those levels covary with the morphology and motility of sperm. This contributes useful knowledge to our understanding of how birds that breed opportunistically (whenever conditions are suitable) manage trade-offs between different physiological traits. Whilst many birds have a very seasonal pattern of breeding, with a flush of hormones and production of sperm arriving with the lengthening days of spring, zebra finches remain reproductively active throughout the year. In the desert, conditions can be suitable for breeding throughout the whole year, depending on when the rain falls.

We showed that testosterone levels were fairly low across different breeding stages, but did significantly increase at the time when a males’ partner is about to become fertile again (as one set of offspring are about to fledge. The higher level of testosterone makes sense, because we demonstrated that higher testosterone is related to the swimming performance of sperm.

Fig 4. From Hurley et al (2023). The relationship between sperm swimming speed and the testosterone level in his blood (A) and his body condition (B).

Bill colour preference does not play a major role in the sub-species barrier between red- and yellow-billed long-tailed finches

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In the paper published in Ecology & Evolution, we report on experiments in which we assessed mate choice by both females and males for members of the opposite sex with bills colours that were either the same as their own, or those of the alternate sub-species. These findings differ from those found in some other hybridising species, where colour signals make an important contribution to pre-copulatory species barriers. The findings help us to understand the evolutionary processes that maintain the divergence between the two forms in the wild across northern Australia. The full paper, led by Callum McDiarmid, and part of his PhD on speciation in this species, can be found here.

The Distribution of the two sub-species of the long-tailed finches across northern Australia with the shading indicating bill colour, with a narrow hybrid zone between the two forms.

Despite the lack of clear assortative mating on the basis of bill colour, the displacement of the contact zone illustrated above in orange, with the area in which most of the genomic divergence occurs (shown with a dashed line), suggests the introgression of the bill colour genes from the west towards the east. This finding can be partly explained by the potential dominance of at least some of the genes for bill colour. In our study we report the findings from experimental crosses between the subspecies in captivity where the colour of the bill in female F1 hybrids is dependent on their father, supporting this idea.

4 PhD opportunities in Avian Evolutionary Ecology in Sydney, Australia

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1 PhD scholarship on ‘Mitonuclear incompatibility and speciation in Poephila finches’ 

3 PhD opportunities: ‘Physiological adaptation to Lead (Pb) contamination in an urban bird’; ‘Personality and behavioural responses to a lead-contaminated environment in an urban bird’; ‘Spatial and behavioural ecology of the endangered black-throated finch’.

We offer 1 full scholarship for an Australian candidate (or competitive International candidate), on the first project listed above (recently supported by ARC funding). For all other projects International or Domestic (Aus/NZ) candidates will be supported in their applications to apply for competitively awarded Macquarie University Scholarships. All projects will be based at Macquarie University, Sydney, Australia.

Sydney is a global power city rated in the world’s top-ten for economy, research and development, cultural interaction, live-ability, environment, and accessibility. Macquarie University is a major research-based institution situated in the heart of Sydney’s high technology precinct. It is considered one of Australia’s best universities and is rated among the top 1% of universities globally. 

School of Natural Sciences, Faculty of Science and Engineering, MQ, is a vibrant community of teachers, researchers, professional staff and students working across a wide range of disciplines including animal behaviour, climate change, conservation, ecology, evolution, genetics and genomics, physiology, and environmental science. 

The PhD’s will all be based in the research group run by Prof. Simon Griffith (https://griffithecology.com), and will be supported by his international collaborators in Europe and the US. 

Projects

Mitonuclear incompatibility and speciation in Poephila finches 

This project is focused on captive and wild populations of Poephila finches that are endemic to northern Australia. This project will examine the incompatibility between the mitochondrial and nuclear genomes, its effect on mitochondrial respiration, and how that contributes to the species barrier between divergent forms. The work is in collaboration with Daniel Hooper (US) and Antoine Stier (France), and will use bioinformatics and physiological assays mostly in the laboratory. 

Physiological adaptation to Lead (Pb) contamination in an urban bird

We have identified resistance to lead poisoning in the population of house sparrows in Broken Hill, Australia’s oldest and largest mining towns. This project will examine the molecular and physiological mechanisms that allow sparrows in this population to thrive in this heavily contaminated environment, providing a case study of evolution in an urban/industrial environment. This project will be based in the field and laboratory and use a combination of molecular and physiological assays.

Personality and behavioural responses to a lead-contaminated environment in an urban bird

This project will focus on the house sparrow population of Broken Hill and investigate the personality traits and spatial and behavioural ecology that permit sparrows to thrive in the heavily contaminated areas of the town. The project will largely be based in the field, in the town of Broken Hill, NSW. 

Spatial and behavioural ecology of the endangered black-throated finch

There is an urgent need to understand the spatial and behavioural ecology of the southern black-throated finch, one of Australia’s most iconic endangered birds. The work will be focused on a remnant population of birds near Townsville and investigate movement ecology with automated radio-tracking in parallel with studies of breeding and behavioural ecology to identify key vulnerabilities. The work will be in collaboration with Lyanne Brouwer (JCU, Townsville, QLD), and require long periods of fieldwork. 

References

Poephila speciation

Lopez KA, McDiarmid CS, Griffith SC, Lovette IJ, Hooper DM (2021) Evaluating evidence of mitonuclear incompatibilities with the sex chromosomes in an avian hybrid zone. Evolution, 75, 1395-1414; Hooper DM, Griffith SC, Price TD (2019) Sex chromosome inversions enforce reproductive isolation across an avian hybrid zone. Mol Ecol, 28, 1246-1262. 

Urban contamination

Andrew SC, Taylor MP, Lundregan S, Lien S, Jensen H, Griffith SC (2019) Signs of adaptation to trace metal contamination in a common urban bird. Sci. Total Environ. 50, 679-686. 

Black-throated finch conservation

Reside AE et al (2019) How to send a finch extinct. Env. Sci & Policy 94 163-173. 

Qualifications

We are looking for a candidate who:

  • holds a (research) master degree or honours degree with distinction* in a relevant field, such as Evolutionary Biology
  • is curiosity driven and passionate about fundamental research in the context of evolutionary ecology, and strongly motivated to obtain a PhD degree
  • is proficient in the English language* 
  • is a team player, willing to work with a diverse group of researchers and technicians, and can also work independently 

*Specific requirements as (see: https://www.mq.edu.au/research/phd-and-research-degrees/how-to-apply)

Ideal candidates will also have some of the following

  • previous experience of bird ringing (or animal handling) and conducting fieldwork in harsh environments 
  • strong quantitative skills in statistics and bioinformatics 
  • have strong communication skills and motivation to disseminate results to both scientific peers and a broad audience

Conditions

Macquarie University offer an MQRES Scholarship, for the duration of the PhD. The scholarship comprises the equivalent of a full-fees award and stipend at the current rate of AU$ 32,000 per annum.

Application
The selection procedure will proceed in three stages:

  1. First application (17/02/23)
  2. Development and submission of full application (International 03/03/23; Domestic 30/04/23) Assessment by selection committee (mid-June)
  3. Start of PhD enrolment for successful candidates (07/08/23)

Please submit your initial application via email to simon.griffith@mq.edu.au before 11:59 pm 17th February 2023. Provide the following in your application:

  1. Cover letter (1 page max.): a letter introducing yourself, describing your motivation and qualifications to conduct this scientific research, and your expectations of the PhD programme
  2. CV (2 pages max.)
  3. Academic records (transcript of undergraduate degree and a certified copy or scan of your MSc or honours degree certificate. 
  4. Proof of sufficient competence in English e.g. IELTS, TOEFL scores. (unless your degree was in an English speaking country)
  5. Names and contact details of two academic references
  6. Initial research project idea: brief description of the research question(s) that you wish to address with respect to the advertised topic and your approach to address the research question(s) (300 words max.)

Applications that do not satisfy the requested format will not be taken into consideration. 

Macquarie University, is committed to providing a working environment where each individual is valued, respected and supported to progress. Our priority is to ensure culture, policies and processes are truly inclusive and that no-one is disadvantaged on the basis of their Aboriginal and Torres Strait Islander identity, gender, culture, disability, LGBTIQA+ identities, family and caring responsibilities, age, or religion. We encourage everyone who meets the selection criteria and shares Macquarie University’s values of scholarship, empowerment and integrity to apply. Learn more about our progress towards Equity, Diversity and Inclusion: https://staff.mq.edu.au/work/diversity-and-community.

Information

For information you can contact:

Zebra finches help to shine a light on the social function of bird song

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In a paper published today in Current Biology, we have characterised the very social nature of song in the zebra finch, and this helps to highlight the fact that bird song is not always about competition over mates and territories. In the study, led by Hugo Loning, a student in Marc Naguib’s research group in Wageningen University (Netherlands), we have analysed the expression of song over several years and in a variety of contexts. The study is an amalgamation of data collected by remote acoustic recorders every three days at Fowlers Gap for several years, across a lengthy drought, and periods of breeding and no breeding activity. The main finding are that zebra finches sing a lot regardless of the season, or condition of the local environment. Males usually sing in the presence of their female partner (who they are typically paired with for life), and also in close company with other males. We believe that our findings should place a greater emphasis on the social function of birdsong more generally, and that it is a useful signal for the coordination of activity across a population of birds. Our findings are in contrast with the great majority of studies of bird song that emphasise the competitive nature of bird song.

There is a piece written about the work in Macquarie’s Lighthouse magazine which includes some video of singing males.

Assessing the danger of climate change to birds

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Tito’s first paper was published today in Conservation Physiology. The paper, which includes some of Tito’s data, is a response to a recent model that had evaluated the likely effects of climate change on some of Australia’s birds. In our response, we used data from our study of the zebra finch to argue that the assumptions that are commonly made about the effects of a warming climate on birds are often over simplistic and aren’t able to account adequately for the adaptive responses that birds are likely to make. For example, in the paper we show that one of the important responses that birds will make on extremely hot days is to drink significantly more water than normal. If birds can stay adequately hydrated they are able to use that water to reduce their body temperature significantly and guard against hyperthermia. We also argue that there is an urgent need to get better physiological data from the zebra finch and other species to improve the value of predictive models in the future. The climate is changing and more extremely hot days are likely. That does cause a significant challenge for birds and there will be a tipping point for survival at some temperature. That point is likely to be slightly higher than the one predicted by earlier models though given the remarkable adaptive responses that we have demonstrated in the zebra finch. The full paper can be found here.

When it gets hot zebra finches drink more, and make use of the many artificial water points across the arid landscape such as this stock watering trough. (photo: Simon Griffith)

Tiarne’s thesis submitted

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 The physiological effects of high blood lead levels in the House sparrow 

Congratulations to Tiarne Harris who submitted her MRes thesis today. Well done on all the amazing work you have put in over the past 12 months. I’m really excited about the results that you have found in the Broken Hill sparrows and the future research directions that they have stimulated.

Tiarne (left) and Lori out at Lex’s in South Broken Hill collecting some of her data.

The evolution of colourful eggs

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It is great to see Kiara’s paper now published in Evolution (it can be found here). The paper is focused on the evolution of colour in eggs and uses the Australian passerines to provide insight into the emergence of pigmented eggs in different branches of the family tree. The passerines, are the songbirds, and they make up about half of the world’s species of bird today. This group first evolved in Australia, and the continent is still home to the largest number of passerine families, and can provide insight into what was happening early in the radiation of the group.

In this study we characterised the egg colour variation across different families of Australian songbird, and were able to identify that the ancestral egg colour in the passerine group was most likely to be white, and that pigmented eggs emerged independently in a number of different branches of the family tree over time. Importantly, this seems to have happened after the ancestors of the different families evolved open nests. This makes sense, because the pigment likely evolved to help protect the now exposed eggs from predators and from solar radiation.

This paper builds nicely on the earlier comparative work that was started with Jordan Price, when he visited on sabbatical and Daisy Englert Duursma.

Fig 2. from L’Herpiniere et al 2021, showing how the evolution of colour in the eggs of different species, maps nicely on to the distribution of closed and open nests across the phylogeny of Australian passerines.

Singing it softly

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Singing male Zebra Finch. (Photo Hugo Loning)

Zebra finch song is an extremely short-range signal. That is the conclusion from the recent paper by Hugo Loning in Behavioral Ecology. This is the first paper of our project on acoustic communication of the wild zebra finch in collaboration with Marc Naguib from Wageningen University. After quantifying the song amplitude of wild zebra finch recordings, we played them back at natural amplitude and re-recorded them in our field site Fowlers Gap. Afterwards, we analysed these transmitted vocalisations while integrating what is known about the hearing from lab zebra finches. This way, we found out that the detection distance of song is on average about nine meters – an extremely short distance for song. We supported this claim by observations in the field which confirm that group members are often very close, on average within one meter, when a group member is singing. Additionally, we find that even their ‘distance call’ does not reach very far, up to about fourteen meters. Our reported findings are in stark contrast with the classical idea of birdsong as a long-range communication signal. The paper can be freely accessed here.

Cover Page Model

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It clearly helps to work on an amazingly beautiful species when it comes to getting a cover page photo for a study, and once again a journal has chosen to use a picture of the Gouldian finch to grace the cover. Here is the August cover of the Journal of Experimental Biology with a great photo supplied by Mark Chappell, one of the co-authors of our new paper. The paper, led by Bill Buttemer demonstrates that although the red and blackheads morphs have some quite different behavioural strategies there is no difference in their basal and maximal metabolic rates.

A male black-headed and male red-headed Gouldian finch.